Ionic liquids are relatively new “green” solvents and generally possess high thermal stabilities and low vapor pressures. Further, ionic liquids are also slightly miscible in water and have a wide liquid range as a result of the wide range of cations and anions that can be combined to form the ionic liquid. Generally, ionic liquids possess a bulky organic cation and an associated anion, as shown for example, in Scheme 1.

Recently, imidazolium based ionic liquids were used to replace conventional organic solvents in free radical polymerizations.1-7 In addition, research has been conducted at the interface of the three different fields of free radical chemistry [8, 9], photochemical reactions [10] and ionic liquids [11, 12].
The styrene monomer (SM) is the immediate precursor for all forms of polystyrene (PS). The polymerization reaction is represented in Scheme 2, which is typically a free radical propagation.

Polystyrene is a common polymer found in a wide range of products, from disposable cutlery to Styrofoam-brand packing material. The polystyrene industry is worth more than $28 billion in the U.S. alone. Generally, this process is carried out on an industrial scale using volatile organic solvents, which are harmful to the environment.